Logical circuits and memory



June 22, 1965 R. R. sEEBER, JR.. ETAL 3,191,155

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JUN 22, 1965 R. R. SEEBER. JR., ETAL 3,191,155

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LGICAL CIRCUITS AND MEMORY Filed Aug. 22. 1960 19 Sheets-Sheet 7 June 22, 1965 R. R. sEEBER, JR.. ETAL 3,191155 LOGICAL CIRCUITS AND MEMORY Filed Aug. 22. 1960 19 Sheets-Sheet 8 June 22, 1965 R. R. sEEBER. JR.. ETAL 3,191,155

LOGICAL CIRCUITS AND MEMORY Filed Aug. 22. 1960 19 Sheets-Sheet 9 June 22, 1965 R. R. sEEBER, JR.. ETAI. 3,191,155

LOGICAL CIRCUITS AND MEMORY Filed Aug. 22. 19Go 19 sheets-sheet 1o June 22 1965 R. R. sEEBER, JR.. ETAL 3,191,155

LOGICAL CIRCUITS AND MEMORY Filed Aug. 22. 1960 19 Sheets-Sheet 1l June Z2, 1965 R. R. sEEBER, JR., ETAL 3,191,155

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June 22, 1965 R. R. sEEBER. JR.. ETAL 3,191,155

LGICL CIRCUITS AND MEMORY Filed Aug. 22. 1960 19 Sheets-Sheet 13 June 22, 1965 R. R. sEEBER, JR., E'rAl. 3,191,155

LOGICAL CIRCUITS AND MEMORY 19 Sheets-Sheet 14 Filed Aug. 22, 1960 June 22, 1965 R. R. sEEBER, JR., rA|. 3,191,155

LOGICAL CIRCUITS AND MEMORY 19 Sheets-Sheet 15 Filed Aug. 22, 1960 19 Sheets-Sheet 16 R. R. SEEBER JR.. ETAI- LOGICAL CIRCUITS AND MEMORY Filed Aug. 22, 1960 June 22, 1965 June 22, 1965 R. R. sEEBER, JR., ETAL 3,191,155

LOGICAL CIRCUITS AND MEMORY Filed Aug. 22. 1960 19 Sheets-Sheet 17 R. R. sEEBER, JR., ETAI.. 3,191,155

LoGIcAL crnoumys AND Muomr June 22,1965

19 Sheets-Sheet 18 Filed Aug. 22. 1960 June 22, 1965 R. R. sEEBER, JR.. ETAL 3,191,155

LOGICAL CIRCUITS AND MEMORY med Aug. 22, 19Go 19 sheets-sheet 19 X C z w w mmm v @E r U V w w rzm s@ \1 l msm o I mgm Ezm l Umm-m o Il.' lll United States Patent O 3,191,155 LOGICAL CIRCUITS AND MEMORY Robert R. Seeber, Jr., Poughkeepsie, and Arthur J.

Scriver, Jr., Wappingers Falls, NX., assignors to International Business Machines Corporation, New

York, N.Y., a corporation of Delaware Filed Aug. 22, 1960, Ser. No. 51,102 2 Claims. (Cl. S40-172.5)

This invention relates to logical circuits of the kind useful in data processing, and more particularly to logical circuits in an associative memory system.

Associative memory systems are those in which a unit of data, such as a Word, is identified for retrieval by specifying the information content of an arbitrary portion of the word structure, known as the tag of the word, which may extend over the entire word or only a part thereof.

The most common type of associative memory systems contain a plurality of Word registers, each register comprising` storage locations for a plurality of bits, the system being adapted to receive words of information serially, the bits of each word being trmansmitted in parallel. As is known in the associative memory art, it is possible to have each word register identify itself as either occupied or vacant, so that data may be placed into word registers which are vacant. Thus, in the present state of the art, associative memories have vacancy responsive means to control the storage of data, and tag comparing means to control the retrieval of data, and are capable of satisfactorily performing the necessary storage and retrieval functions, However, in order to achieve maximum utilization of the associative type of memory system, the storage and retrieval of information performed in dependence only upon vacancy status of registers and tag comparison of words is insufiicient. Maximum adaptability of data handling can be achieved only if additional controls over the operation of the memory are provided. The large numbers of data bits and word registers needed to provide a useful associative memory requires that the means employed be extremely simple, inexpensive and of low power consumption; the provision of additional control functions accentuates these requirements. In order to provide simple arrangements ot' logical elements which lend themselves to practical production techniques, only the most refined logical circuits can be employed.

It is an object of this invention to provide an associative memory apparatus in which information having common tags and an additional sequential relationship can be stored and retrieved while preserving said sequential relationship.

Other objects of the invention include the following:

To provide an associative memory system having sequentially responsive word registers;

To provide an associative memory system in which the retrieval of information is controlled in part by the sequence in which information is stored in said system;

To provide an associative memory system in which information having like tags can be retrieved on a firstin/rst-out basis;

To provide an associative memory system in which in` `formation may be retrieved from a sequence of word 3,191,155 Patented June 22, 1965 registers in turn, each supplying information and thereafter rendering the next word register in sequence operative to read out information, in dependence upon having the proper tag;

To provide an associative memory system in which each word register in a sequence of word registers is controlled in part by the vacancy and tag-comparison status of the word registers antecedent thereto;

To provide an associative memory system, employing current gates, comprised of a plurality of word registers each having a fixed number of components per word register without regard to the number of Word registers contained in said apparatus;

To provide an associative memory system, employing current gates capable of being embodied in any size and yet having a fixed number of control components per word register;

To provide improved logical circuits of the type useful in associative memories;

To provide improved vacancy controlling circuits of the type useful in an associative memory system;

To provide vacancy-controlled tag comparing circuits of the kind useful in controlling an associative memory system;

To provide improved logical circuits responsive to both the vacancy and tag functions in an associative memory system.

Our present invention comprises an associative memory system wherein each one of a sequence of word registers is caused to be interrogated for vacancy or tag comparison purposes in a fixed order, as determined by its position in said sequence. Briey, the logical circuits of our invention are interconnected in series with one another in such a fashion that comparable logical circuits of subsequent Word registers are made operative or rendered responsive in the same sequence as the word registers to which they appertain. The vacant or occupied status of each Word register controls the testing for vacancy of each subsequent Word register, and the operative fact of match or mismatch during a tag comparing operation of each register Will determine whether or not a subsequent register is to be tested for a match.

In accordance with our invention, a repetitive retrieval operation may be performed. In our device, the registers are tested both for vacancy and for matching tags in sequence, so that the first register with the proper tag is read out; after said register has been read out, it will render the next one of a sequence of registers operative to respond (if it contains the proper tag, etc.), so that subsequent read-out operations can be performed on the registers in sequence, and the information retrieved will have the same sequential relationship as the registers in which it was stored. Since selection of the registers in which the information is stored depends on the order in which storage is effected, the sequence of retrieval will directly correspond to the sequence in which information is stired in the apparatus. This permits sequential storage of information as well as sequential retrieval thereof, together providing the possibility of word groupings and maintaining a maximum amount of available storage space within the apparatus. Furthermore, inadvertent use of the same tag information in more than one word will not cause the information content of either register to be lost, it being possible to retrieve the information 

1. IN AN ASSOCIATIVE MEMORY OF THE KIND IN WHICH GROUPS OF DATA BITS STORED IN RANDOM ONES OF A SEQUENCE OF REGISTERS ARE IDENTIFIED BY A TAG PORTION OF EACH GROUP, AND IN WHICH THE TAG OF A GROUP WHICH IS TO BE RETRIEVED FROM MEMORY IS COMPARED WITH THE TAGS OF ONE OR MORE OF THE GROUPS STORED THEREIN, A CONTROL DEVICE FOR SELECTING THE ONE OF SAID REGISTERS FROM WHICH DATA IS TO BE RETRIEVED, COMPRISING: A VACANCY CONTROL MEANS FOR EACH OF SAID REGISTERS, EACH INCLUDING A VACANCY DESIGNATING MEANS AND AN OCCUPANCY DESIGNATING MEANS ALTERNATIVELY OPERABLE IN DEPENDENCE ON WHETHER THE CORRESPONDING REGISTER IS VACANT OR OCCUPIED, RESPECTIVELY; A TAG COMPARING MEANS FOR EACH OF SAID REGISTERS, EACH RESPONSIVE TO THE OCCUPANCY DESIGNATING MEANS OF THE CORRESPONDING REGISTER, EACH INCLUDING A MATCH RESPONSIVE MEANS AND A MISMATCH RESPONSIVE MEANS ALTERNATIVELY OPERABLE IN DEPENDENCE ON WHETHER THE TAG OF THE DESIRED GROUP AND THE TAG OF THE GROUP STORED IN THE CORRESPONDING REGISTER ARE IDENTICAL OR NOT, RESPECTIVELY; A READ-OUT MEANS FOR EACH OF SAID REGISTERS, EACH OPERABLE IN RESPONSE TO THE CORRESPONDING ONE OF SAID MATCH RESPONSIVE MEANS TO RETRIEVE DATA FROM THE CORRESPONDING REGISTER; A CONNECTION MEANS FOR EACH REGISTER SUBSEQUENT TO THE FIRST ONE IN SAID SEQUENCE, EACH CONCURRENTLY RESPONSIVE TO THE MISMATCH RESPONSIVE MEANS AND THE VACANCY DESIGNATING MEANS OF THE REGISTER ANTECEDENT THERETO IN SAID SEQUENCE TO OPERATE THE ONE OF SAID VACANCY CONTROL MEANS CORRESPONDING TO SAID SUBSEQUENT REGISTER; AND INITIATING MEANS TO START A RETRIEVAL OPERATION BY OPERATING THE VACANCY CONTROL MEANS OF THE FIRST REGISTER IN SAID SEQUENCE. 